Dialkyl selenoxide hydronitrates

ABSTRACT

DIALKYL SELENOXIDE HYDROMITRATES HAVING THE STRUCTURAL FORMULA   R1-SE(=O)-R2.HNO3   WHEREIN R1 IS AN ALKYL RADICAL HAVING FROM 8 TO 18 CARBON ATOMS, R2 IS AN ALKYL RADICAL HAVING FROM 1 TO 14 CARBON ATOMS AND THE SUM OF R1 PLUS R2 IS NOT GREATER THAN 28 CARBON ATOMS, ARE USEFUL GERMICIDES IN DETERGENT COMPOSITIONS.

United States Patent Office 3,642,909 Patented Feb. 15, 1972 3,642,909 DIALKYL SELENOXIDE HYDRONITRATES Hill M. Priestley, North Bergen, N.J., assignor to Lever Brothers Company, New York, N.Y.

No Drawing. Continuation-impart of application Ser. No. 656,325, July 27, 1967. This application Dec. 15, 1969, Ser. No. 885,298

Int. Cl. C07c 163/00 US. Cl. 260-607 R 11 Claims ABSTRACT OF THE DISCLOSURE Dialkyl selenoxide hydronitrates having the structural formula wherein R is an alkyl radical having from 8 to 18 carbon atoms, R is an alkyl radical having from 1 to 14 carbon atoms and the sum of R plus R is not greater than 28 carbon atoms, are useful germicides in detergent compositions.

This application is a continuation-in-part of my copending US. application Ser. No. 656,325, filed July 27, 1967, now abandoned.

The present invention relates to novel chemical compounds which are dialkyl selenoxide hydronitrates.

The dialkyl selenoxide hydronitrates of the invention have the general structural formula wherein R is an alkyl radical having from 8 to 18 carbon atoms, R is an alkyl radical having from 1 to 14 carbon atoms and the sum of R plus R is not greater than 28 carbon atoms. Preferably the sum of R plus R is not greater than 24 carbon atoms. It is also preferred that R is an alkyl radical having from 1 to- 2 carbon atoms. The R alkyl radicals are exemplified by octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl, while the R alkyl radicals are exemplified by methyl, ethyl, propyl, butyl, amyl, hexyl, octyl, nonyl, decyl, dodecyl and tetradecyl. Typical compounds of the invention include octyl methyl selenoxide hydronitrate, decyl methyl selenoxide hydronitrate, dodecyl methyl selenoxide hydronitrate, tetradecyl methyl selenoxide hydronitrate, hexadecyl methyl selenoxide hydronitrate, octadecyl methyl selenoxide hydronitrate, octyl ethyl selenoxide hydronitrate, decyl ethyl selenoxide hydronitrate, dodecyl ethyl selenoxide hydronitrate, tetradecyl ethyl selenoxide hydronitrate, hexadecyl ethyl selenoxide hydronitrate, octadecyl ethyl selenoxide hydronitrate, di-octyl selenoxide hydronitrate, di-decyl selenoxide hydronitrate, di-dodecyl selenoxide hydronitrate, ditetradecyl selenoxide hydronitrate, octyl amyl selenoxide hydronitrate, nonyl dodecyl selenoxide hydronitrate, octadecyl decyl selenoxide hydronitrate and decyl propyl selenoxide hydronitrate.

The dialkyl selenoxide hydronitrates, unlike the dialkyl selenoxides, are stable on storage at room temperature and hence do not decompose into malodorous alkyl selenomercaptans. They are also stable in neutral and acidic solutions. However, in alkaline solutions they decompose into the unstable free dialkyl selenoxides. They may be stabilized in alkaline solutions by adding 3-7 sodium nitrate thereto as a preservative.

The dialkyl selenoxide hydronitrates may be prepared in the classical manner by oxidizing the corresponding dialkyl selenides with concentrated nitric acid in accordance with the following equation:

wherein R and R including the sum thereof, are as stated above.

The dialkyl selenoxide hydronitrates of the invention are useful as germicides. The compounds are particularly attractive in this regard in that they are effective germicides against gram positive organisms and also against gram negative organisms which are generally harder to kill thn the gram positive organisms. Comparative germicidal tests have shown that the compounds of the invention are generally superior to 3,4',S-tri-bromosalicylanilide, a Well known germicide, in their elfectiveness against some gram positive organisms and gram negative organisms. The remarkably unexpected effectiveness of the compounds of the invention in killing Pityrosporum ovale, an organism associated with dandruff, indicates the important utility of these compounds as antidandruff agents in shampoos. In addition to their property as germicides, the longer chain length compounds of the invention, i.e., wherein R is dodecyl to octadecyl, also have utility as lime soap dispersants, suds boosters and foam stabilizers.

The following examples are illustrative of the preparation of typical dialkyl selenoxide hydronitrates of the invention.

EXAMPLE 1 Preparation of tetradecyl methyl selenoxide hydronitrate To 15 ml. of concentrated nitric acid contained in a 250 ml. Erlenmeyer flask, there was added dropwise 32 gm. of tetradecyl methyl selenide, with cooling and stirring. The addition required about /2 hour. The mixture was poured, in a fine stream, into a liter of cold water, with vigorous stirring. The solid was broken up into fine particles, and filtered on a Buchner funnel. The filtrate was clear. In the presence of free nitric acid, the hydronitrate does not disperse in water. The solid was washed on the funnel with distilled water until the filtrate became cloudy. The material was air dried, and then dried in the vacuum desiccator. The yield was 39 gm. The melting point was not sharp. The hydronitrate softened at C., and melted completely at C. The crude hydronitrate, 20.5 gm., was recrystallized from 125 ml. ethyl acetate, to give 19- gm. of the same melting point characteristics: softening at 77 C. and completely melting at 90 C. The infrared spectroscopic'curve for the'tetradecyl methyl selenoxide hydronitrate product had a. broad peak at 7-8 micron Wavelength which is characteristic of dialkyl selenoxide hydronitrates.

EXAMPLE 2 Preparation of octyl methyl selenoxide hydronitrate To 15 ml. of concentrated nitric acid contained in a 125 ml. Erlenmeyer flask, there Was gradually added, with cooling and stirring, 13.1 gm. of octyl methyl selenide having a boiling point of C. at 20 mm. pressure. On the addition of 45 ml. of cold distilled water, with stirring, an oil separated on the bottom of the flask. The oil solidified when the flask was placed on a block of Dry Ice. The Erlenmeyer flask was then transferred to a water-ice bath. The solid did not melt. It was broken up into fine particles with a glass rod and filtered on a Buchner funnel. The hydronitrate was washed with a mixture of 15 ml. concentrated nitric acid and 45 ml.

water, and dried to constant weight at room temperature. This was accomplished by spreading the moist hydronitrate on a procelain dish and placing it in the hood in a draft of air. The yield of air-dried material was 11.98 gm. and it had a melting point of 5060 C. This octyl methyl selenoxide hydronitrate product also has an infrared spectroscopic curve having a broad peak at 78 micron wavelength.

EXAMPLE 3 Preparation of hexadecyl methyl selenoxide hydronitrate Hexadecyl methyl selenide, 29.3 gm., boiling point 158 C. at 1 mm. pressure, was added in small portions to 50 ml. of concentrated nitric acid in a 250 ml. Erlenmeyer flask. The operation was accomplished without too much cooling, otherwise the material in the flask solidified. The mixture was poured into a liter of distilled water. The solid was broken up and filtered on a Buchner funnel, and washed with 50 ml. of distilled water. The washings were still acid to litmus. The moist solid was spread on an evaporating dish (5% diameter, 2" depth) and air-dried in the hood to constant weight. The yield was 35.8 gm. The hydronitrate softened at 80 C., melted completely at 105 C., and decomposed at 130 C. The hexadecyl methyl selenoxide hydronitrate product also has an infrared spectroscopic curve having a broad peak at 7-8 micron wavelength.

GP p.p.m MEC p.p.m 90 mm. mm. growth Therefore, the lower the MEC value, the higher the germicidal activity.

The test organisms employed were Streptococcus faecalis (Sf), Micrococcus candidus (Mc), Escherichia coli (Ec), Salmonella choleracsuis (Sc), Pseudomonas acruginosa (Ps) and Pityrosporum ovale (Po). It will be noted that the Sf and Mc organisms are gram positive organisms while the Ec, Sc and Ps organisms are gram negative organisms. As pointed out heretofore, the Po organism is that one which is associated with dandruff.

The germicidal activity of representative dialkyl selenoxide hydronitrates of the invention was measured by the above procedure and the results are given in the following Table I. The germicidal activity of the heretofore known methyl phenyl selenoxide hydronitrate and 3,4',5- tribromosalicylanilide compounds is also set forth in the following Table I for comparative purposes:

TABLE I MEG in p.p.m.

Percent active ingredients Si Me Ee Sc Ps Po Octyl methyl selenoxide hydronitrate 32 267 2-14 444 24 Decyl methyl selenoxide hydronitrate 21 25 42 48 467 5. 5 Dodeeyl methyl selenoxide hydronitrate 28 24 25 39 53 8. 3 Tetradecyl methyl selenoxide hydronitrate 25 18 36 37 43 18 Hexadeeyl methyl selenoxide hydronitrate 27 26 100 100 100 31 Octadecyl methyl selenoxide hydronitrate, 43 37 1, 000 1,000 100 Di d0deeyl selenoxide hydronitrate 4. 4 0 1,000 53 Methyl phenyl selenoxide hydronitrate 5O 53 59 58 1, 000 3,4,fi-tribromosalieylanilide 100 100 1,000 1, 000 1, 000 100 The other dialkyl selenoxide hydronitrates of the invention may be prepared by oxidizing the corresponding dialkyl selenides with concentrated nitric acid and purifying in the same manner as described in the preceding illustrative examples.

The germicidal activity of the dialkyl selenoxide hydronitrates was determined by the following test procedure:

Streak gradient plate mtehod for the determination of germicide minimum effective concentration (MEC) values Inclined base layers of 13 ml. of simple nutrient agar per plate are poured by means of a Brewer automatic pipettor onto square Falconware phage dishes. The dishes are placed on an inclined (1:16) platform so that the base layer hardens in the form of a wedge. The platform is then levelled for addition of a germicide/agar layer.

Germicide/agar mixtures are prepared by pipetting less than 1 ml. aliquots of 0.2% (2,000 p.p.m.) stock germicide solutions into sterile test tubes and adding 13 ml. of agar to each tube by an automatic pipettor. The dilutions employed range from 0.075 to 102 p.p.m. (GP) of germicide in agar.

The agar dilutions are decanted from the tubes onto the base-layered plates and hardened in a level position. The direction of the gradient is labelled, and streak inoculations are performed in the same direction.

Culture suspensions are prepared from 2448 hour slant cultures of the test organisms given below by washing the surface with 10 ml. sterile 0.1% peptone water. Sterile No. 1 artist brushes are employed by streaking these suspensions across the surface of the plate.

It will be noted from the data set forth in the above Table I that the representative dialkyl selenoxide hydronitrates of the invention are effective germicides against both gram positive and gram negative test organisms, especially against Pityl'osporum ovale (Po), and are generally more effective against the test organisms than is 3,4,S-tribromosalicylanilide, a well-known germicide, in view of their lower MEC values.

The lime soap dispersant property of representative dialkyl selenoxide hydronitrates of the invention was determined by the following test procedure:

Lime soap dipsersion test The lime soap scum dispersion test consists of agitating 35 ml. of 1% (Lux soap flake plus agent, i.e., hydronitrate) solution at 45 C. in a Waring blendor for 1 minute at 8500 rpm. After 30 seconds the lather is quenched with 750 ml. of Water having a hardness of 180 p.p.m. (2 Ca-l Mg) at 40 C., and then the surface is visually rated for scum. The mixture is then stirred for seconds with a mechanical stirrer after which the system is visually rated for solution clarity and foam. .It is finally filtered over a black cloth and the reflectance increase is read on the Hunter Refiectometer.

The visual observation rating scale for foam, surface scum and solution clarity is 0=poor; 2=fair; and 4=good; i.e., the higher the rating, the better the dispersant. For reflectance increase, on the other hand, the lower the value, the better the dispersant.

The results of this test are given in the following 2. The dialkyl selenoxide hydronitrates defined by Table II: claim 1 wherein the sum of R plus R is not greater than TABLE II Percent Surface Solution Reflectance Agent agent 1 Foam scum clarity increase Octyl methyl selenoxide hydronitrate 2O 1% 10. 3 Deeyl methyl selenoxide hydronitrate. 0 3 9. 1 Dodecyl methyl selenoxide hydronitrate 20 l 1% 2 0.1 Tetradecyl methyl selenoxide hydronitrate 20 1% 2% 2% 0.0 Hexadeeyl methyl selenoxide hydronitrate. 20 2 2 2% 0. 0 Octadecyl methyl selenoxide hydronitrate. 20 2 1 1 0i 1 Dodecyl ethyl selenoxide hydronitrate 20 2% 0. 7 Di-dodecyl selenoxide hydronitrate 20 0 1% 9. 3 Lux flakes (control) 0 0 2 11. 1

agent 1 Percent agent=- agent+soap In the above Table II the reflectance increase is the most important measurement of lime soap dispersant property. For a material to function ideally as a lime soap dispersant, the reflectance increase should be a value less than 1. In this connection, it will be noted that the reflectance increase 'values for the control LuX flakes, the octyl methyl, decyl methyl and di-dodecyl selenoxide hydronitrates of the invention are all greater than 1 and hence these materials are poor in lime soap dispersant property. However, the remaining dialkyl selenoxide hydronitrates given in Table II above were highly satisfactory lime soap dispersants, since the reflectance increase values therefor were all less than 1.

What is claimed is:

1. Dialkyl selenoxide hydronitrates having the structural formula wherein R is an alkyl radical having from 8 to 18 carbon atoms, R is an alkyl radical having from 1 to 14 carbon atoms and the sum of R plus R is not greater than 28 carbon atoms.

References Cited Paetzold et al., Chemical Abstracts, vol. 67 (1967), page 81759.

CHARLES B. PARKER, Primary Examiner D. R. PHILLIPS, Assistant Examiner U.S. Cl. X.R. 

